Hello again @DJ_Jamba,
I was actually talking about your original answer itself. I had tried the flow that you suggested:

But it gave me the same error:

Hence I tried the same thing that you suggested, but in a slightly different way, where I added an extra test. But you can ignore that for now, and we can go back to discussing this error 🙂

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Again, just for additional info, the output from "List rows present" is:
{"body":{"value":[{"@odata.etag":"","ItemInternalId":"80d8d372-650a-4424-b4bf-9d8ce5fab243","Name":"Deadline 1","Deadline":"45372","Project Finished":"Yes","Deadline Met/Was":"Achieved"},{"@odata.etag":"","ItemInternalId":"28aff3b5-b572-4651-a564-d6589a6eb5ea","Name":"Deadline 2","Deadline":"45372","Project Finished":"No","Deadline Met/Was":"0"},{"@odata.etag":"","ItemInternalId":"08d40502-aaf8-4924-8508-1500c9c4fd4e","Name":"Deadline 3","Deadline":"45376","Project Finished":"No","Deadline Met/Was":"4"},{"@odata.etag":"","ItemInternalId":"a7806b49-58f8-49e7-8c94-be3ce3729fea","Name":"Deadline 4","Deadline":"45366","Project Finished":"","Deadline Met/Was":"-6"},{"@odata.etag":"","ItemInternalId":"33ca2ab3-907a-436d-97de-a704079dce5c","Name":"Deadline 5","Deadline":"45369","Project Finished":"Yes","Deadline Met/Was":"Achieved"},{"@odata.etag":"","ItemInternalId":"3f25b32d-2243-4b5e-99a3-e66900e4ce63","Name":"Deadline 6","Deadline":"45370","Project Finished":"No","Deadline Met/Was":"-2"},{"@odata.etag":"","ItemInternalId":"5964d4a2-da7f-47f9-ae02-3f785ab4fc03","Name":"Deadline 7","Deadline":"45374","Project Finished":"Yes","Deadline Met/Was":"Achieved"},{"@odata.etag":"","ItemInternalId":"bf7ad988-2750-41f7-b4b1-3492589750dd","Name":"Deadline 8","Deadline":"45444","Project Finished":"","Deadline Met/Was":"72"}]}}